I'm very interested to see what happens to Chansey. To be honest I can't see it being deemed "BL" simply due to usage due to the fact that there will be plenty of fighters to take it out: Medicham, Blaziken, hell I even considered Machoke for this job, and there's still Hitmontop, Primape or Hitmonlee if people feel like using them (not to mention they will have outstanding coverage against the Regi's too.)
SO I believe that based on usage Chansey will "look" fine, but are it's base stats that different to Blissey's, my initial thoughts were "no", and I'll explain why, Max HP / Max Def Blissey only takes physical hits slightly worse than the old 252 HP / 252 Def Blissey, when the base stats are that low (10 Def for Blissey, 5 Def for Chansey) it doesn't make a whole lot of difference, the only "real" difference is that of Special attack (which Blissey isn't exactly renowned for), so what bothers me about it is the fact that Chansey might not be "broken" in UU, but may remain in the tier, doing exactly the same job that Blissey would have done should we have put her in the tier =/
Now we may decide that that's not an issue because OU is based entirely on Usage anyway, and if that is the case, so be it. The system that we have works, but it's at least an interesting way of looking at it, if chansey works in the new tier, lets keep it there. (Am I the only one working on offensive teams here?)
@ below poster - indeed it could just use Seismic Toss, I did say that Blissey isn't exactly renowned for it's special attacking ability, Chansey is even less so, making it likely that it will be Chansey's attacking move of choice.